I have Alen T300. It is whisper quiet unit with good performance. I wanted to buy smaller unit for bedroom and ordered T100 expecting it to be similar to T300. Only similarity between these two units though is design and HEPA filter - T300 uses two TF30 filters and T100 only one. T100 has also lower power consumption - 13Wt at low speed compared with 20Wt for T300. But it is louder - 39 db vs 36 db. Those 3 db make all the difference (3 db doubles audible sound level). When I sleep with T300 on in low speed I virtually do not hear it running when it is 5 feet away. But T100 sounds like air conditioner when running under same circumstances. And it additionally moves twice less air. Sound of motor and pitch of moving air in case of T100 is less pleasant than in T300. It all sums up to the fact that T100 is not for bedroom use. And even when I use it for other purposes its sound irritates if there is no other source of sound (like TV or PC).
I looked into interior of both units and discovered that motor-fan combo in T300 is higher quality than in T100. E.g. in T300 electric motor is open and seems traditional while in T300 it is closed design with closed bearings which reduces noise.
T100 pros are - it is small and portable, you can carry it with you anywhere you want. It does a good air cleaning - according to [...] it cleans air much better than typical value oriented purifier. Another plus is attractive design and ease of use. So I am thinking about buying another T300 to run in my bedroom while using T100 as portable air purifier.Get more detail about Alen T100 Desktop Air Purifier.